package me.weijing.common.xmpp.manager;

import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

/**
 * This class add a sort by insertion to a List. All methods which allow you to
 * insert an object at a specific index will throw an
 * UnsupportedOperationException.
 * 
 * @author Da Risk <da_risk@beem-project.com>
 * @param <E>
 *            the type of elements maintained by this list
 */
public class SortedList<E> implements List<E> {

    private final List<E> mBackend;
    private final Comparator<? super E> mComparator;

    /**
     * Create a SortedList. The existing elements will be sorted.
     * 
     * @param list
     *            list to sort
     * @param mComparator
     *            mComparator to use.
     */
    public SortedList(final List<E> list, final Comparator<? super E> mComparator) {
        this.mComparator = mComparator;
        this.mBackend = list;
        Collections.sort(mBackend, mComparator);
    }

    @Override
    public int size() {
        return mBackend.size();
    }

    @Override
    public boolean isEmpty() {
        return mBackend.isEmpty();
    }

    @Override
    public boolean contains(Object o) {
        return mBackend.contains(o);
    }

    @Override
    public Iterator<E> iterator() {
        return new SortedListIterator<E>(mBackend.listIterator());
    }

    @Override
    public Object[] toArray() {
        return mBackend.toArray();
    }

    @Override
    public <T> T[] toArray(T[] a) {
        return mBackend.toArray(a);
    }

    @Override
    public boolean add(E e) {
        for (ListIterator<E> it = mBackend.listIterator(); it.hasNext();) {
            if (mComparator.compare(e, it.next()) < 0) {
                if (it.hasPrevious()) {
                    it.previous();
                }
                it.add(e);
                return true;
            }
        }
        mBackend.add(e);
        return true;
    }

    @Override
    public boolean remove(Object o) {
        return mBackend.remove(o);
    }

    @Override
    public boolean containsAll(Collection<?> c) {
        return mBackend.containsAll(c);
    }

    @Override
    public boolean addAll(Collection<? extends E> c) {
        boolean result = false;
        for (E e : c) {
            boolean t = add(e);
            if (t) {
                result = t;
            }
        }
        return result;
    }

    /**
     * Add all the elements in the specified collection. The index param is
     * ignored.
     * 
     * @param index
     *            ignored
     * @param c
     *            collection containing elements to be added to this list
     * @return true if this list changed as a result of the call
     */
    @Override
    public boolean addAll(int index, Collection<? extends E> c) {
        return addAll(c);
    }

    /**
     * Add all the elements in the specified collection. The index param is
     * ignored.
     * 
     * @param l
     *            collection containing elements to be added to this list
     * @return true if this list changed as a result of the call
     * @see addAll(Collection)
     */
    public boolean addAll(SortedList<? extends E> l) {
        if (!l.isEmpty()) {
            if (mBackend.isEmpty()) {
                return mBackend.addAll(l);
            }
            boolean result = false;
            E myfirst = mBackend.get(0);
            E last = l.get(l.size() - 1);
            E mylast = mBackend.get(mBackend.size() - 1);
            E first = l.get(0);
            if (mComparator.compare(last, myfirst) < 0) {
                result = mBackend.addAll(0, l);
            } else if (mComparator.compare(first, mylast) > 0) {
                result = mBackend.addAll(l);
            } else {
                Collection<? extends E> c = l;
                result = addAll(c);
            }
            return result;
        }
        return false;
    }

    @Override
    public boolean removeAll(Collection<?> c) {
        return mBackend.removeAll(c);
    }

    @Override
    public boolean retainAll(Collection<?> c) {
        return mBackend.retainAll(c);
    }

    @Override
    public void clear() {
        mBackend.clear();
    }

    @Override
    public boolean equals(Object o) {
        return mBackend.equals(o);
    }

    @Override
    public int hashCode() {
        return mBackend.hashCode();
    }

    @Override
    public E get(int index) {
        return mBackend.get(index);
    }

    @Override
    public E set(int index, E element) {
        throw new UnsupportedOperationException("set() is not supported in SortedList");
    }

    @Override
    public void add(int index, E element) {
        throw new UnsupportedOperationException("add at specific index is not supported in SortedList");
    }

    @Override
    public E remove(int index) {
        return mBackend.remove(index);
    }

    @Override
    public int indexOf(Object o) {
        return mBackend.indexOf(o);
    }

    @Override
    public int lastIndexOf(Object o) {
        return mBackend.lastIndexOf(o);
    }

    @Override
    public ListIterator<E> listIterator() {
        return new SortedListIterator<E>(mBackend.listIterator());
    }

    @Override
    public ListIterator<E> listIterator(int index) {
        return new SortedListIterator<E>(mBackend.listIterator(index));
    }

    @Override
    public List<E> subList(int fromIndex, int toIndex) {
        return mBackend.subList(fromIndex, toIndex);
    }

    @Override
    public String toString() {
        return mBackend.toString();
    }

    /**
     * A SortedList.iterator don't allow list modification. It use the mBackend
     * iterator for the other operations.
     */
    private class SortedListIterator<E> implements ListIterator<E> {

        private ListIterator<E> mIt;

        /**
         * Construct SortedList.Iterator.
         * 
         * @param iterator
         *            the iterator of the backend list
         */
        SortedListIterator(final ListIterator<E> iterator) {
            mIt = iterator;
        }

        @Override
        public void add(E e) {
            throw new UnsupportedOperationException("add() not supported in SortedList iterator");
        }

        @Override
        public boolean hasNext() {
            return mIt.hasNext();
        }

        @Override
        public E next() {
            return mIt.next();
        }

        @Override
        public boolean hasPrevious() {
            return mIt.hasPrevious();
        }

        @Override
        public E previous() {
            return mIt.previous();
        }

        @Override
        public int nextIndex() {
            return mIt.nextIndex();
        }

        @Override
        public int previousIndex() {
            return mIt.previousIndex();
        }

        @Override
        public void remove() {
            mIt.remove();
        }

        @Override
        public void set(E e) {
            throw new UnsupportedOperationException("set () not supported in SortedList iterator");
        }
    }
}
